Soak sultanas in rum and lid. Keep in fridge to soak, preferably overnight
Mix bit of milk with cornflour until smooth set aside.
Put rest milk, single cream, sour cream and sugar in pan and heat gently until sugar dissolves
Stir in cornflour mix and stir until thick and coats back of spoon. Take off heat and leave to cool.
Pour mix in large container that fits in fridge and stir in raisins and any rum left in container. Leave to chill 30 minutes plus
Turn ice cream maker on paddles turning pour mixture in and leave to run for the 60 minutes or until the machine stops or you get your preferred consistany. I set mine another 20 minutes.
Serve immediately or put in a container & freeze